DIY Hydronic Heat in Garage

monty26

It looks like there are some good knowledgeable people on this forum and just hoping to run through some numbers on a pump and water heater or boiler so I don't completely screw up. I have to use non-condensing due to not having a drain.

I just built a 30x60 garage with an average 14ft ceiling, r19 walls and r49 roof deck. 5/8" pex tubing in 6 loops, lengths are 283,290,295,302,286, and 297 created with LoopCAD. 2" rigid foam under pad and around. I think I put everything into LoopCAD to calculate BTU and head loss. It didn't ask for anything about the tankless/boiler for head loss though. I will vary the temp between 55 and 70.

55* set point = water temp 85*, 7.03gpm, 12.8 head loss, 31127 BTU
70* set point = water temp 107*, 8.89gpm, 17.7 head loss, 39349 BTU

I was thinking of using a taco 0014 pump and a RL94IN tankless to meet the requirements of 70* and hoping it will work fine for 55* that it will be at usually. What do you think? You can say I'm crazy and get a pro, but hopefully I'm not far off... TIA

Zman

If you are not going with condensing, why not buy an atmospheric boiler and install a smart mixing valve like a Taco I-series. If you use a cast-iron model, you could probably use a single circulator.
Tankless water heaters are not designed for the duty cycles you need for heating and have high internal flow resistance.

EBEBRATT-Ed

As far as no drain you could use a condensate pump.

What is the RL94IN tankless for or are you using a tankless water heater for a boiler? The 0014 is ok if your head calcs are correct, not much margin for error may want an 0012

mattmia2

Keep in mind that if you think you are going to use setback with that setup it is likely to take days to get to the higher temp with the slab as the only source of heat. Might think of adding a unit heater or something as another higher temp zone for recovery.

psb75

No one seems to like the tankless. What's up with that?
It heats water doesn't it? It should be able to heat a building...right?

PC7060

Tankless as designed for shorter and fewer dirty cycle than what will be required for your applications.  I’d get a modcon; well suited for the purpose and I’ve found they can be bought for less than a tankless WH. 

mattmia2

A modcon will have the controls for a boiler built in(thermostat connection, pump relays, setpoint for domestic heating, outdoor reset, some sort of short cycle protection settings, etc.), a tankless water heater will not.

You could just drain it outside by gravity if you are above ground.

Zman

psb75 said:

No one seems to like the tankless. What's up with that?
It heats water doesn't it? It should be able to heat a building...right?

It will heat water, it will require a larger circulator, won't last as long, and does not have outdoor reset.

It will heat water

monty26

Wow, love this forum, quick input.

Zman said:

If you are not going with condensing, why not buy an atmospheric boiler and install a smart mixing valve like a Taco I-series. If you use a cast-iron model, you could probably use a single circulator.
Tankless water heaters are not designed for the duty cycles you need for heating and have high internal flow resistance.

Thank you, haven't seen anything about an atmospheric in any of my searches, will look into that.

EBEBRATT-Ed said:

As far as no drain you could use a condensate pump.

What is the RL94IN tankless for or are you using a tankless water heater for a boiler? The 0014 is ok if your head calcs are correct, not much margin for error may want an 0012

House is 200ft away and up a hill 30ft to the septic, so condensate is a no go. Yes, was looking into a tankless water heater as the boiler due to low btu requirements and not needing a mixing valve with it.

mattmia2 said:

Keep in mind that if you think you are going to use setback with that setup it is likely to take days to get to the higher temp with the slab as the only source of heat. Might think of adding a unit heater or something as another higher temp zone for recovery.

Interesting. I would hope it's hours and not days, but then again I may turn it up a little if I know I'm doing work, but 70 would only be the absolute highest temp for some random reason.

mattmia2 said:

A modcon will have the controls for a boiler built in(thermostat connection, pump relays, setpoint for domestic heating, outdoor reset, some sort of short cycle protection settings, etc.), a tankless water heater will not.

You could just drain it outside by gravity if you are above ground.

It is above ground, but won't the output freeze easily? I'm in a suburb of Chicago so it can get down to -20*F now.

mattmia2

I'm not an expert on how to route condensate out in to a freezing environment, but it will be about the temp of the return water temp when it leaves the boiler, i think as long as you slope it so it doesn't sit in the condensate line and you have a couple feet between the trap in the boiler and where the pipe goes outside it won't freeze.

ratio

monty26 said:

Interesting. I would hope it's hours and not days, but then again I may turn it up a little if I know I'm doing work, but 70 would only be the absolute highest temp for some random reason.

Days might be a stretch (might!), but hours are pie in the sky. You've got to heat tons of concrete, which then heat the space.

JUGHNE

If ModCon cond drain is run directly outside thru the wall it will dribble and eventually freeze the pipe shut. The same if dumped into an UG drain line that is shallow bury and little other water flow activity.

What has worked for me, and I am in a little colder area then the OP, is to use the standard cond pump.
I put a vertical stand pipe (3/4" PVC) inside the heated building within 6" of the ceiling.
Then take the PVC thru the exterior wall at a 45 degree angle so the end terminates about 18"+ above grade. (best on the sunny side of the building).

Pump the condensate into the top of the inside standpipe. Leave an air gap for venting the drop pipe. (3/8" tubing stuck inside 3/4" pipe only 6" will do this).

This removes the water in batches, shooting it outside in one shot, with little chance of freeze up. The outside discharge pipe must be above grade enough to not create an icicle connecting the pipe to the ground.


And as far as a tankless WH, those are designed to heat water running thru them at your house pressure of maybe 50 PSI. Heating system will not be anywhere near that pressure. It has been done.... with a lot of grief involved....as proven here by others who tried it in the past.

You will pretty well have to maintain the floor temp with no set backs.

If you want quick heat, add hanging gas powered infrared radiant heater to the areas of the building where you might be working. Exhaust vented to the outside.

And if this is a garage then all sources of ignition must be at least 18" above the floor.
If you go with cast iron boiler, it must have combustion air brought into the building.

This is one of the few times I would recommend a ModCon over CI.

Zman

The mod/con would likely save 10% over a properly sized cast iron boiler.

Zman

If you are going to be creating dust in the garage, the modcon or a sealed combustion copper fin tub would be worth considering. Pulling combustion air from outdoor vs the space is worth considering.

monty26

I have changed by mind about using a water heater and go with a Rinnai I090SN condensing boiler and just putting some heat wrap around the discharge line where it exits the building and using a condensate pump to push it out instead of let it dribble.

My calcs above were just for the tubing and 6-loop manifold. It looks like the boiler adds another 17ft head at ~9gpm, am I reading that correct? If that is the case, can I just use 1 pump like a Taco 2445 without a primary-secondary(hydraulic separation) heating kit. Or do I have to use the primary-secondary heating kit with 2 pumps like a 007(Rinnai recommends) for the boiler pump and and a 0013 for the loops?

EBEBRATT-Ed

@monty26

If Rinnai recommends primary secondary than that is what you should do. Most mod cons have a high pressure drop

Rich_49

monty26 said:

I have changed by mind about using a water heater and go with a Rinnai I090SN condensing boiler and just putting some heat wrap around the discharge line where it exits the building and using a condensate pump to push it out instead of let it dribble.

My calcs above were just for the tubing and 6-loop manifold. It looks like the boiler adds another 17ft head at ~9gpm, am I reading that correct? If that is the case, can I just use 1 pump like a Taco 2445 without a primary-secondary(hydraulic separation) heating kit. Or do I have to use the primary-secondary heating kit with 2 pumps like a 007(Rinnai recommends) for the boiler pump and and a 0013 for the loops?

Why not just use the IO60SN and save some cash , It's large enough for your loads . It has an integral circ for the boiler . Pipe it P/S and use the 0014 as you originally stated , if you're not comfortable with the 14 , use the 0013 , it has a higher head and GPM capability . Forget about the 0012 , it's curve moves in the wrong direction as it is a low head high flow circ , you require a higher head low flow circ . The 2445 is nothing you should even be considering .

https://s3.amazonaws.com/s3.supplyhouse.com/product_files/Rinnai-I060SN-Brochure.pdf




The reason tankless water heaters are a bad idea is that most require a minimum pressure through the heat exchanger of 25 PSI . Used in a closed loop system that would require a crazy circ . 1 PSI = 2.31 feet of head , I'll let you do the math .

Just figure a way to get rid of the condensate .

monty26

Rich_49 said:

Why not just use the IO60SN and save some cash , It's large enough for your loads . It has an integral circ for the boiler . Pipe it P/S and use the 0014 as you originally stated , if you're not comfortable with the 14 , use the 0013 , it has a higher head and GPM capability . Forget about the 0012 , it's curve moves in the wrong direction as it is a low head high flow circ , you require a higher head low flow circ . The 2445 is nothing you should even be considering .

https://s3.amazonaws.com/s3.supplyhouse.com/product_files/Rinnai-I060SN-Brochure.pdf

I figured the I060SN and I090SN has the same min BTU and it's only about $100 more, so why not go bigger just in case.

I was caught off by the brochure also, it shows there is an internal pump, but the install manual says there isn't on page 56. I'm good with using the 14 if there is an actual internal pump, I may have to call Rinnai. From what it looks like, only the I060CN combi's have the internal pump.

https://media.rinnai.us/salsify_asset/s-5d95909c-a518-426c-8255-d9507f2f51b3/800000112-I-Series Condensing Solo Boiler Installation and Operation Manual.pdf?_ga=2.167806241.1885684328.1640126851-35787186.1638905894

Rich_49

Nothing marrying you to a Rinnai , is there ? Research other brands , although the IO60 only requires a 007 as a boiler circ , not a high dollar item by any stretch . HTP and NTI are both Ariston brands now and have a very good water tube boiler that does in fact have an integral boiler circ , for similar money as the Rinnai .

https://htproducts.com/literature/mktlit-97.pdf

https://ntiboilers.com/wp-content/uploads/2019/08/NTI_TRX-Series-Handout_2020_Final_Web-1.pdf

Both exactly the same boiler .

monty26

Rich_49 said:

Nothing marrying you to a Rinnai , is there ? Research other brands , although the IO60 only requires a 007 as a boiler circ , not a high dollar item by any stretch . HTP and NTI are both Ariston brands now and have a very good water tube boiler that does in fact have an integral boiler circ , for similar money as the Rinnai .

https://htproducts.com/literature/mktlit-97.pdf

https://ntiboilers.com/wp-content/uploads/2019/08/NTI_TRX-Series-Handout_2020_Final_Web-1.pdf

Both exactly the same boiler .

Definitely not married to Rinnai. Thank you, I do like those 085 boilers, they even go to a lower min BTU. Now to see where I can actually purchase them.

mattmia2

Htp at least a couple years ago was also rebranded as Westinghouse. Note you dont have to buy their low loss header kit you can make it with your own closely spaced tees.

Rich_49

mattmia2 said:

Htp at least a couple years ago was also rebranded as Westinghouse. Note you dont have to buy their low loss header kit you can make it with your own closely spaced tees.

Not re branded . HTP bought licensing from Westinghouse to increase market share in the Mid West and other areas . Most of those units were sold through Menards